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Decimal

by gmatblood » Wed Nov 02, 2011 11:59 am
Q1

What is the hundredth digit of the decimal Z?
1. The tenth digit of 100Z is 2
2. The unit digit of 1000Z is 2

Q2

Is the hundredths digit of the decimal d greater than 5?
(1) the tenths digit of 10d is 7.
(2) the thousandths digit of d/10 is 7.

Please point the takeaways as well, thanks
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Source: — Data Sufficiency |
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by gmatblood » Wed Nov 02, 2011 12:02 pm
Detailed explanation needed, not just IMO!!
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by rijul007 » Wed Nov 02, 2011 12:29 pm
Q1

lets say z = abc.lmn
we need the value of a..

Statement 1
10th digit of 100z is 2

100z = abclm.n
l=2
Insufficient

Statement 2
unit digit of 1000Z is 2
1000z = abclmn
n=2

Insufficient


Combinig 1 and 2
we get z = abc.2m2

Still Insufficient


Option E


Takeaway
You need to analyze what the ques is really asking for.
In this ques, u can rephrase the ques as
What is a?[if z=abc.lmn]
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by rijul007 » Wed Nov 02, 2011 12:36 pm
Q2

Is the hundredths digit of the decimal d greater than 5?
Rephrase it as
Is c>5? [d = abcxy.lmn]

Statement 1
the tenths digit of 10d is 7

10d = abcxyl.mn
y=7
Insufficient

Statement 2
the thousandths digit of d/10 is 7
a=7
Insufficient

Combining 1 and 2[/]
Insufficient


E

d/10 = abcx.ylmn
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by mankey » Sun Nov 06, 2011 6:40 am
Someone please help on this one. This one is not clear.

Thanks.
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by shankar.ashwin » Sun Nov 06, 2011 9:15 am
What is the hundredth digit of the decimal Z?
1. The tenth digit of 100Z is 2
2. The unit digit of 1000Z is 2

First thing, you need to know what hundredth position actually means;

If you have a number say 123.456

Here note the decimal place value of each number,
1 - hundreds
2 - tens
3 - ones/units
4 - tenths
5 - hundredths
6 - thousandths (Notice whatever ends in 'ths' comes to the right of the decimal point)

In this problem, consider a number of the form A.BCD

hundredths is 'C' here;

we need to find 'C'

Statement 1;
tenth digit of 100Z is 2

100Z = ABC.D

tenth digit - D. We cannot find 'C' - insufficient

Statement 2:
1000Z - ABCD

unit digit of 1000Z is 2
unit digit - 'D'

Again this gives us 'D'. we cannot find 'C'.
Both statement actually give us the same value. Hence E IMO
mankey wrote:Someone please help on this one. This one is not clear.

Thanks.
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by shankar.ashwin » Sun Nov 06, 2011 9:21 am
Is the hundredths digit of the decimal d greater than 5?
(1) the tenths digit of 10d is 7.
(2) the thousandths digit of d/10 is 7.
Again consider a number of the form A.BCD.

hundredths place is 'C'

Statement 1
10d = AB.CD

tenths digit of 10d is 7 - C is 7, which is > 5. Sufficient

Statement 2
d/10 = 0.ABCD

the thousandths digit of d/10 is 7 - C is 7, which is > 5. Sufficient.

Both statements give you value of 'C' here. D IMO
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